Small-type thermostat for preventing overheating, provided with a bimetal disk in a lenticular casing and with beam-like profiled bracing means on said casing



3,096,418 PROVIDED A. oDENwALD July 2, 1963 SMALL-TYPE THERMOSTAT R PREVENTING OVERHEATING WITH A BIMETAL DISK IN A LENTICULAR CASING AND WITH BEAM-LIKE PROFILED BRACING MEANS ON SAID CASING 1959 2 Sheets-Sheet 1 Filed April 7 United States .Patent O 3,096,418 SMALL-TYPE THERMOSTAT FOR PREVENTING OVERHEATING, PROVIDED WITH A BIMETAL DISK IN A LENTICULAR CASING AND WITH BEAM-LIKE PROFILED BRACING MEANS ON SAID CASING Alfred Odenwald, Steinberg'sgutstrasse, Pforzheim, Germany Filed Apr. 7, 1959, Ser. No. 804,772 Claims priority, application Germany Apr. 18, 1958 4 Claims. (Cl. Zim- 138) The present invention relates to a small-type thermostat and is particularly directed to a thermostat for preventing overheating iny electrical apparatus las well as in windings of machines and transformers, and which is provided with a curved bimetal disk supported in its position at the rim of the casing, whereby the bimetal disk is preferably equipped in its center in conformity with the German patent (application 0.2355, VIIIb/Zlc) with a rivet contact of high-grade contact material wh-ich co-operates with a counter rivet-contact at the casing.

When building small-type thermostats of this type into windings, which thereupon are lacquered and dried in known manner, it has been found that these thermostats, because of the contraction during the drying process, are exposed to considerable pressure, whereby however thick walls of the casing have to be avoided in order to ensure a :speedy transition of the heat, that is to say, a quick reaction. Particularly when pouring onto the coil ends under vacuum, Ias is necessary for motors stable toward water and acids and safeguarded against explosion, and dur-ing the wrapping and the solidication of the insulating material, as well as during the subsequent drying in the furnace the small-type thermostat is exposed to very high pressure which it has to resist.

According to the invention there has been produced a small-type thermostat indifferent against pressure by providing a lenticular casing with a profiled cover and bottom part, preferably of the beam-like profiled type, whereby a yielding or compression of the casing even under strongest pressure is reliably avoided. It has to be taken into consideration that already a slight yielding of the wall of the casing would result in switching faults of the birnetal disk, which however has now been reliably avoided by the profiled bracing means of the invention. Furthermore, this beam-like profiled structure increases in advantageous manner the size of the surface of the cover and bottom parts `for the quicker absorption and emission of the heat, so that the small-type thermostat can produce a still more favorable effect.

According to the invention it is further possible to also employ a lenticular casing provided with a cover and bottom part consisting of sheet-metal adapted for re-tempering, preferably of a copper-beryllium alloy, whereby the connection at the rim is preferably effected by means of a flanged-over rim-ring, as a hanged-over rim connection of the ordinary type is no longer possible for the retempered parts.

In "a construct-ion like this the ring `at the rim of the casing may have the shape of a double-angle in such manner that the common leg between the two angles serves as support for the cover part and bottom part to rest against, while the free angles are flanged over and secure the cover part and bottom part in their position, and if necessary are Isoldered to the parts to provide a vacuumtight connection. This permits a pouring under vacuum onto the coils provided with the small-type thermostats of the invention, las this is necessary for under-water motors as well as for motors stable against acid and explosions.

3,096,418 Patented July 2K, 1963 ICO ln addition to this there may be arranged in the flattened portion of the bottom part of the casing a reinforcing basin, whereby the rivet-counter-contact of the casing forces the conductor rings with the laid of the tensioning plates and the intermediate elastic insulating member against the flattened portion of the casing, so that a particularly useful and tight form of construction is obtained.

Additional features and advantages of the invention will be understood from a consideration of the following detailed description taken in connection with the accompanying drawings forming a part of this specification and in which an embodiment of the invention has been shown by way of example. However, I wish to say that the invention is not confined to any strict conformity with the showing of the drawings but may be changed or modified, so long as such changes or modifications mark no material departure from the salient features of the invention as expressed in the appending claims.

In the drawings, in which like parts are referred to by the :same reference numerals,

FIG. l is a central sectional view of the small-type thermostat of the invention provided with armoring or bracing means at the cover-part and at the bottom-part of the casing;

FIG. 2 is la front view of the armored cover-part of the casing;

FIG. 3 is a sectional view on line III-III of the armored cover-part;

FIG. 4 is a sectional view on line IV-IV of the yarmored cover-part;

FIG. 5 is a front view of the armored bottom-part of the casing;

FIG. `6 is a sectional view on line VI-VI of the armored bottom-part;

FIG. 7 is a sectional view on line VI-I-VII of the armored bottom-part.

As will be seen from the drawings, not only the cover part 1 but also the bottom part 2 of the lenticular casing are provided with beam-like bracings 3` and 4 for their reinforcement. According to a further inventive idea the cover part 1 @and the bottom part 2 may be produced with and without beam-like bracing means from sheetmetal adapted for re-tempering, preferably from a copperberyllium alloy, whereby not only a perfect conducting power for heat but also an armoring effect is obtained. In this construction there is employed for the joining of the edges of the cover part and bottom part a ring of substantially T-shapeid cross-section 5, 6 in which the control portion 5 serves `as a support for the cover and bottom parts 1 and 2 to rest against, while the ange portions 6 ,are flanged over for fastening to the two parts and if necessary also are tightened and packed through soldering. Within the lenticular casing 1 and 2 there is positioned in conformity with the main-patent the bimetal disk 7 provided with the rivet-contact 8 which co-operates with a counter-rivetcontact 9 at the attened portion 10 of the bottom part 2. 4In a double acting switching arrangement it is also possible to provide a counter-contact 9 on both sides of the center contact S (not shown in the drawings). Positioned within the flattened portion 10 of the bottom part 2 is an insulating member 11 in the shape of a reinforcing basin. Positioned upon the flattened portion 10 and insulated from the contact 9 is the conductor ring 12 for the casing. Then follows the elastic insulating mem ber 13, and then the conductor ring 14, which is in contact with the counter-rivet-contact 9. Two pressure plates ensure with the aid of the oounter-rivet-contact 9 and the insulating members 11 and 13 a vacuum tight kand stable current connection. In the switch position illustrated in the drawing the current passes from the ring conductor E 14 via the contact 9 of the casing, the switch contact S, the bimetal disk 7 to the casings 1 and 2 and then from the bottom part 2 off lagain via the ring conductor 12. Reversing or snapping in opposite direction of the bimetal disk 7 interrupts the current conduction or reverses it accordingly.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A 4small type thermostat adapted to be inserted between windings of electrical machinery to prevent overheatings thereof and comprising, in combination, a casing of lenticular shape including a pair of oppositely curved sheet metal members having each an annular edge face directed toward the annular edge face of the other of said members, and a metal ring of substantially T-shaped cross-section having a central portion and a pair of curved iiange portions integral with and protruding respectively from opposite sides of said central portion, said central portion being located between and engaged on opposite sides thereof by said edge faces of said sheet metal members, respectively, and said pair of tlange portions respectively engaging outer surface portions of said :sheet rnetal members adjacent said edge faces thereof so as to press said edge faces tightly against said central portion of said ring so as to form together with said central portion of said ring an annular outwardly closed space; a birnetal disk extending transversely through said casing in the fregi-on of said central portion of said ring and having a rim portion projecting into and located in `said annular space formed by said central portion of said ring and said pair of oppositely curved sheet metal members, so that isaid bilmetal disk is thereby supported yand properly centered within said casing; a irst contact iixed to said disk substantially in the center thereof; a counter contact iXed to and insulated from one of said sheet metal members of said casing and aligned with said rirst contact; and la pair of conductor means respectively electrically and mechanically connected to said casing and said counter contact. i

2. An arrangement as defined in claim l in which said sheet metal members are made from tempered copperberyllium alloy.

3. An Iarrangement -as defined in claim 1 in which said bimetal disk has a thickness substantially equal to that of said central portion of said ring and an outer diameter substantially equal to the inner diameter of said central portion.

4. An arrangement as dened Vin cla-im 1 in which said ange portions are soldered to said outer surface portions of .said sheet metal members.

References Cited in the le of this patent UNITED STATES PATENTS 470,653 Bell et al Mar. 15, 1892 1,106,844 Ream Aug. 11, 1914 `1,654,822 Lafite a Jan. 3, 19218 1,7 617,709 Smith J une 24, 1930 2,442,726 Gstalder June l, 1948 2,732,461 Huber Ian. 24, 1956 2,811,611 Odenwald Oct. 29, 1957 FOREIGN PATENTS 250,099 Switzerland May 18, 1948 303,430 Switzerland ---au Feb. 1, 1955 799,002 Great Britain July 30, 1958 

1. A SMALL TYPE THERMOSTAT ADAPTED TO BE INSERTED BETWEEN WINDINGS OF ELECTRICAL MACHINERY TO PREVENT OVERHEATINGS THEREOF AND COMPRISING, IN COMBINATION, A CASING OF LENTICULAR SHAPE INCLUDING A PAIR OF OPPOSITELY CURVED DIRECTED TOWARD THE ANNULAR EDGE FACE OF THE OTHER OF SAID MEMBERS, AND METAL RING OF SUBSTANTIALLY T-SHAPED CROSS-SECTION HAVING A CENTRAL PORTION AND A PAIR OF CURVED FLANGE PORTIONS INTEGRAL WITH AND PROTUDING RESPECTIVELY FROM OPPOSITE SIDES OF SAID CENTRAL PORTION, SAID CENTRAL PORTION BEING LOCATE BETWEEN AND ENGAGED ON OPPOSITE SIDES THEREOF BY SAID EDGE FACES OF SAID SHEET METAL MEMBERS, RESPECTIVELY, AND SAID PAIR OF FLANGE PORTIONS RESPECTIVELY ENGAGING OUTER SURFACE PORTIONS OF SAID SHEET METAL MEMBERS ADJACENT SAID EDGE FACES THEREOF SO AS TO PRESS SAID EDGE FACES TIGHTLY AGAINST SAID CENTRAL PORTION OF SAID RING SO AS TO FORM TOGETHER WITH SAID CENTRAL PORTION OF SAID RING AN ANNULAR OUTWARDLY CLOSED SPACE; A BIMETAL DISK EXTENDING TRANSVERSELY THROUGH SAID CASING IN THE REGION OF SAID CENTRAL PORTION OF SAID RING AND HAVING A RIM PORTION PROJECTING INTO AND LOCATED IN SAID ANNULAR SPACE FORMED BY SAID CENTRAL PORTION OF SAID RING AND SAID PAIR OF OPPOSITELY CURVED SHEET METAL MEMBERS, SO THAT SAID BIMETAL DISK IS THEREBY SUPPORTED AND PROPERLY CENTERED WITHIN SAID CASING; A FIRST CONTACT FIXED TO SAID DISK SUBSTANTIALLY IN THE CENTER THEREOF; A COUNTER CONTACT FIXED TO AND INSULATED FROM ONE OF SAID SHEET METAL MEMBERS OF SAID CASING AND ALIGNED WITH SAID FIRST CONTACT; AND A PAIR OF CONDUCTOR MEANS RESPECTIVELY ELECTRICALLY AND MECHANICALLY CONNECTED TO SAID CASING AND SAID COUNTER CONTACT. 